The present invention relates to a hot rolling process, and more particularly to a method of operating a reheating furnace in a hot rolling line.
Commonly, in modern steel making plants, achievement of energy and labor savings and high efficiency has constantly been sought by making various processes involved continuous. The production line ranging from a continuous casting process to the rolling process has been included in such efforts, and making such process continuous has been attempted by arranging a reheating furnace between the continuous casting machine and the rolling mill. In the conventional arrangements as described above, since the speed for the continuous casting differs to a large extent from that of the rolling, with the latter being normally several times higher than the former, the reheating furnace employed is required to serve as a buffer or absorbing zone for absorbing the difference in through put capacity between the two processes as far as possible. More specifically, in order to meet the requirement as described above, it becomes necessary to employ a reheating furnace capable of simultaneously discharging workpieces for rolling at a higher speed and continuously being charged with workpieces from the casting process at a lower speed without altering the transportation rate of such workpieces. Additionally, such a reheating furnace should be so arranged as to achieve high operating efficiency of the rolling apparatus and labor saving through reduction, as far as possible, of the frequency of on-off operations for the rolling mill operated at high speed by storing therein a predetermined amount of workpieces to be rolled which have been cast continuously at low speed and also by collectively forwarding such workpieces in one group from the furnace to the rolling mill. For the purpose as described above, the reheating furnace must be provided, without increasing the length thereof, with heating and heat holding capability for retaining the heat of heated workpieces to be rolled until the workpiece last charged into the furnace has been heated up to the predetermined rolling temperature.